They copy Opera features but they are still far away from Opera. I thing the problem Opera has still, is that they need a much more stable software.
You're seriously kidding if you think Firefox is more stable than Opera. Check firefox related posts here on DP - even the most ardent fans mention the memory leak issues and upgrade issues with add-ons etc. Your post about Opera's stability simply means you do not use it and as such are unqualified to make any such remarks/comparisons.
I'm in a love triangle between Opera & Firefox... they both are fighting over my love & affection, I feel so torn
maybe the opera always got the BEST until the Firefox 1.0 released. I think the Opera team should face this fact. Both of FX and Opera were installed on my PC for using and testing, they're really good browsers. But FX is much easy to use.
So what was your testing methodology? Your statement leaves out some information which would be beneficial to understand your point. I use both Opera and Firefox. Firefox simply cannot keep up with my browsing speed. I have no issues with Opera in that regard. In my case, Opera keeps up because it has a smaller memory footprint, loads webpages faster, and the mouse-gestures works amazingly quick.